Device for spacing the segments of a commutator

ABSTRACT

A cagelike device having an outer tubular wall and a plurality of spacing strips integral with this wall and projecting radially from the inner side thereof for holding the segments of a commutator at the proper distance from each other during the production of the commutator including the step of filling of the commutator with a molding material.

United States Paten Worner et al,

DEVICE FOR SPACING THE SEGMENTS OF A COMMUTA'IIFUR Anton Worner, Stuttgart; lllelrnut Wilbert, Boblingen, both of Germany Kaut & Burr oHG, Stuttgart-Vaihingen, Germany Filed: July 22, 1970 Appl. No.: 57,160

Inventors:

Assignee:

US. Cl. ..29/205 CM, 29/205 D Int. Cl. .llltlZlt 115/09 Field oi Search ..29/205 CM, 205 D, 205, 203

[56] ltellerenees tCiteti UNITED STATES PATENTS 1,325,325 12/1919 .lanlce ..29/205 CM Primary Examiner--Thomas H. Eager Attorney-Arthur O. Klein [5 7] ABSTRACT A cagelike device having an outer tubular wall and a plurality of spacing strips integral with this wall and projecting radially from the inner side thereof for holding the segments of a commutator at the proper distance from each other during the production of the commutator including the step of filling of the commutator with a molding material.

9 Claims, 4i Drawing Figures PATENIEDFEBEE I972 ..l vemlm's: Am WQRNER Helmui WILBERT A 0 m, Af/m DEVICE FOR SPACING TIIIE SIEGMENTS OF A COMMUTATOR The present invention relates to a device for facilitating the production of a commutator which is filled with a molding material, and more particularly it relates to a device for spacing the segments of such a commutator during its production at the proper distance from each other by means of spacing strips of a plastic which engage with the lateral surfaces of the adjacent segments and are removed from the commutator when it is completed.

Prior to this invention, such devices consisted of individual spacing strips which during the assembly of the segments were inserted between the latter and were removed from the commutator by means of a solvent after the molding material with which the commutator with the exception of its hub was filled was completely solidified. The proper assembly of the individual segments and intermediate spacing strips so as to form an annular body was, however, a rather difficult operation which rendered the production of such commutators rather expensive.

It is an object of the present invention to provide a device for spacing the segments of a commutator of the above-mentioned type at the proper distance from each other in a manner which renders the production of such commutators very economical.

For attaining this object, the present invention provides a device in which prior to their removal from the completed commutator, the individual spacing strips of plastic are integrally connected to each other so as to form a tubular element, hereafter called a cage, which is at first made of a conical shape and the peripheral wall of which is provided on its inner surface with substantially parallel elongated projections which project for a short distance radially toward the inside of this cage and serve as the mentioned spacing strips.

By making this device of a tubular cagelike shape, it is very easily possible to insert or slide the segments between the adjacent spacing strips and to hold them in this position during the further steps of producing the commutator. The conical shape of the cage then not only permits the segments from dropping out, but it also permits them to be more easily inserted, especially if this is done by automatic means. The commutator may thus be very easily handled during the different steps of its production and this may be done automatically by suitable machinery.

According to another preferred embodiment of the invention, the cage is provided with at least one longitudinal slot between each pair of adjacent spacing strips. In order to prevent these slots from dividing the cage into separate parts, both ends of the peripheral wall of the cage are extended beyond the ends of the spacing strips so that a connecting web remains at each end of the wall which is not severed into individual parts by slots. The slots are made of such dimensions that, after the segments have been inserted into the cage and the latter has been inserted into a mold, the cage wall may be shrunk in this mold with the result that the slots will be closed and the segments will be clamped tightly between the spacing stri s.

AFnother preferred feature of the invention consists in making the two connecting webs at the opposite ends of the conical cage wall of different shapes. Thus, while one connecting web merely forms an unslotted tubular extension of the wider end of the cage wall, i.e., that part of the cage wall which extends in the longitudinal direction beyond the ends of the spacing strips, the other connecting web at the narrower end of the cage wall is provided on its inner side with inwardly projecting stop means for limiting the extent to which the segments may be inserted between the spacing strips from the wider end of the cage wall. These stop means on the web at the narrower end of the cage wall are preferably provided in the form of a ring which is integral with the unslotted parts of the cage wall and projects radially inward so as to form a shoulder as a common stop member against which the other ends of all of the segments may abut when inserted between the spacing strips. Since the thickness of this ring including the end part of the cage wall from which the ring projects in the radially inward direction is greater than the other parts of the wall, the slots may also be extended through this end part of the cage wall carrying the ring but will then only form grooves in its outer peripheral surface. The ring as such is therefore unslotted and forms the connecting web of the ends of the spacing strips adjacent to the narrower end of the cage wall as well as a stop member against which one end of all of the segments may abut when inserted into the cage.

If this end of each segment of the commutator is to be pro vided with a pin-shaped extension which is later bent outwardly to form a hook to serve as a soldering terminal, a modification of the invention consists in providing the cage wall to be extended beyond the mentioned ring and in providing this extension of the cage wall and also the part of this wall from which the ring projects inwardly with channels which are adapted to receive the pin-shaped extensions of the segments when the latter are being inserted into the cage.

The aforementioned as well as additional features and advantages of the present invention will become more clearly ap parent from the following detailed description thereof which is to be read with reference to the accompanying drawings, in which FIG. I shows a perspective view of a cage according to a first embodiment of the invention; from which a part is brolten away;

FIG. 2 shows a perspective view of a commutator, partly broken away and in section after it has been filled with the molding material and after the cage as shown in the reverse position in FIG. ll, has been shrunk to a cylindrical shape;

FIG. 3 shows a perspective view of a. part ofa cage similar to that as shown in FIG. I but modified in accordance with a second embodiment of the invention; while FIG. i shows a perspective view of a commutator. likewise partly broken away and in section, which has been produced by means ofa cage as shown in FIG. 3.

Referring first particularly to FIG. I of the drawings, the device according to the invention comprises a cage ll of a conical tubular shape the peripheral outer wall of which is provided with spacing strips 2 which are integral with this wall, extend in the longitudinal direction thereof substantially parallel to each other, and project radially inward from the inner surface of this wall. Each of these spacing strips 2 has a width substantially in accordance with the width of the gap between two adjacent segments 3 of the commutator when completed. After these segments 3 are inserted into the cage and between the spacing strips .2 as shown in FIG. l, the spaces remaining within the commutator are filled with a molding material, as shown in FIG. 2. Centrally between the adjacent spacing strips 2, the cage wall carrying these strips is provided with longitudinal slots d which extend from the narrower end of the cage l to a point near the other wider end and have a length substantially equal to that of the spacing strips 2. Thus, an unslotted margin 5 remains adjacent to this wider end of cage I. At its narrower slotted end, cage l is held together by means of a ring 6 which projects radially from the inner surface of the cage wall and has a radial thickness greater than the depth of the slots t. Therefore, in the part of the cage wall from which the ring 6 projects, the slots l merely form grooves in the outer surface of the cage wall. For molding the cage l, the annular recess in the mold in which the ring 6 is formed also serves for receiving and distributing the molding material for producing the entire cage within the mold. The inner shoulder of ring 6 facing the wider end of the cage wall forms a stop surface against which all of the segments 3 abut when they are inserted between the spacing strips 2, preferably by mechanical means which operate automatically. The conical shape of cage I considerably facilitates the insertion of the spacing strips from the wider end of the cage wall.

After the segments 3 have been inserted between the spacing strips 2, cage I is shrunk within a mold so that the slots t will be closed, the segments 3 will be clamped tightly between the adjacent spacing strips, and cage ll will be changed from its original conical shape to a cylindrical shape, as shown in FIG. 2, i.e., the desired shape of the final commutator. In FIG. 2, the ring 6 is not visible since the cage is turned about an angle of 180 to its position as shown in FIG. 1.

After the commutator has been completed by filling it under pressure with the insulating molding material, the outer wall of cage 1 is removed either mechanically or by being washed off by means of a solvent. A mechanical removal of this wall on a lathe or similar machine is especially advisable if it is necessary to reduce the outer diameter of the completed commutator or to finish its outer surface. The spacing strips 2 may likewise be washed out or be pulled out from the segments 3 by gripping the ring 6 which is integral with one end of the spacing strips 2 and by pulling this ring in its axial direction. This method of removing the spacing strips 2 is of advantage because all spacing strips will then be pulled out simultaneously.

If the outer longitudinal edges of the segments 3 are beveled as shown at 7 in FIG. 2, the base of each spacing strip 2 ad jacent to its connection to the outer wall of the element has to be enlarged accordingly. These beveled edges also facilitate the removal of the spacing strips 2 when the commutator is otherwise completed.

FIG. 3 illustrates a modification of the invention in which the cage 101 which is made of plastic differs from the cage 1 according to FIG. 1 substantially only by being designed for receiving segments 103 which differ from the segments 3 by having pins 107 which project in the longitudinal direction from one end of the segments and are later bent outwardly to form soldering terminals. For receiving these pins 107, the outer wall of cage 101 is provided with an extension 108 which projects longitudinally beyond the ring 106 which projects radially inward. This extension 108 and the part of the cage wall carrying the ring 106 are provided with channels 109 which have a substantially T-shaped cross section the wider inner parts of which are adapted to receive the pins 101 on the segments 103 when the segments 103 are inserted into the cage 101, while the narrower outer parts of these channels 109 which are in continuous straight alignment with the slots 104 correspond to the grooves which are provided in the part of the cage wall carrying the ring 6 as mentioned with reference to FIG. 1 and thus also in the part of the cage wall according to FIG. 3 carrying the ring 106.

Since the terminal pins 107 are thinner or narrower in the peripheral direction of the commutator than the segments 103 themselves, the distance between the inner or wider parts of the adjacent channels 109 also has to be larger than the distance between the adjacent slots or outer grooves 104. Furthermore, in this embodiment of the invention, the front ends of the commutator segments 103 themselves do not abut directly against the ring 106, but against shoulders on the wider parts 110 of the spacing strips 102 adjacent to ring 106. From the free edge portions of these shoulders facing radially toward the central axis of cage 101 the radially inner surfaces of the wider parts 110 of spacing strips 102 are beveled toward the inner edge of ring 106. The result of this structure of cage 102 may be seen in FIG. 4, especially adjacent to the hatched surfaces of the completed commutator where a sector of this commutator is cut away for better illustration.

The segments 103 are inserted into the cage 101 similarly as described with reference to FIG. 1 from the wider side of the cage and preferably by automatically operating mechanical means. The segments then slide between the adjacent spacing strips 103 and their terminal pins 107 into the wider parts of channels 109. The further steps of producing the commutator are substantially the same as described with reference to FIGS. 1 and 2.

Although our invention has been illustrated and described with reference to the preferred embodiments thereof, we wish to have it understood that it is in no way limited to the details of such embodiments but is capable of numerous modifications within the scope of the appended claims.

I-Iavin thus fully disclosed our invention, what we claim is: 1. A evice for spacing the segments of a commutator during its production at a predetermined distance from each other comprising a cage having an outer tubular wall of plastic having at first a conical shape with a wider end and a narrower end, and a plurality of spacing strips integral with and extending in the longitudinal direction of said wall and projecting radially from its inner surface toward the inside of said cage, the lateral sides of each pair of adjacent spacing strips substantially engaging with the lateral sides of one of said segments when said segments are inserted into said cage from the wider end of said wall.

2. A device as defined in claim 1, in which between each pair of adjacent spacing strips said wall is provided with at least one longitudinal slot having a length at least equal to the length of each of said segments, said wall having unslotted portions near both ends thereof for integrally connecting said spacing strips to each other.

3. A device as defined in claim 2, in which the wider end of said wall consists of an unslotted longitudinal extension of the slotted part of said wall.

4. A device as defined in claim 2, in which an end portion of said cage near said narrower end of said wall comprises a part carrying an unslotted ring integral with and projecting radially from the inner surface of said wall.

5. A device as defined in claim 2, further comprising stop means at the inner side of and integral with said wall for limiting the extent to which said segments may be inserted into said cage between said adjacent spacing strips.

6. A device as defined in claim 4, in which said ring has one side facing the wider end of said wall and forming an annular shoulder adapted to serve as a common stop member on which one end of all of said segments abut when said segments are inserted into said cage from the wider end thereof.

7. A device as defined in claim 4, in which said end portion of said cage near said narrower end of said wall further comprises a longitudinal extension of said wall beyond said ring, and a plurality of longitudinal channels each extending continuously through said part of said wall carrying said ring and through said extension of said wall and having a width smaller than the width between two adjacent spacing strips, said channels receiving terminal pins forming extensions of said segments when said segments are fully inserted into said cage.

8. A device as claimed in claim 7, further comprising individual stop members integral with said ring on the inner side of said wall and projecting for a short distance from said ring in the direction toward the wider end of said wall, one end of each of said segments at the point to which one of said terminal pins is connected abutting against at least one of said stop members when said segments are inserted into said cage.

0. A device as defined in claim 2, in which after said segments are inserted into said cage, said cage is shrunk whereby said slots are closed and said segments are tightly clamped between the adjacent spacing strips and said peripheral wall of said cage is changed from its original conical shape to a cylindrical shape. 

1. A device for spacing the segments of a commutator during its production at a predetermined distance from each other comprising a cage having an outer tubular wall of plastic having at first a conical shape with a wider end and a narrower end, and a plurality of spacing strips integral with and extending in the longitudinal direction of said wall and projecting radially from its inner surface toward the inside of said cage, the lateral sides of each pair of adjacent spacing strips substantially engaging with the lateral sides of one of said segments when said segments are inserted into said cage from the wider end of said wall.
 2. A device as defined in claim 1, in which between each pair of adjacent spacing strips said wall is provided with at least one longitudinal slot having a length at least equal to the length of each of said segments, said wall having unslotted portions near both ends thereof for integrally connecting said spacing strips to each other.
 3. A device as defined in claim 2, in which the wider end of said wall consists of an unslotted longitudinal extension of the slotted part of said wall.
 4. A device as defined in claim 2, in which an end portion of said cage near said narrower end of said wall comprises a part carrying an unslotted ring integral with and projecting radially from the inner surface of said wall.
 5. A device as defined in claim 2, further comprising stop means at the inner side of and integral with said wall for limiting the extent to which said segments may be inserted into said cage between said adjacent spacing strips.
 6. A device as defined in claim 4, in which said ring has one side facing the wider end of said wall and forming an annular shoulder adapted to serve as a common stop member on which one end of all of said segments abut when said segments are inserted into said cage from the wider end thereof.
 7. A device as defined in claim 4, in which said end portion of said cage near said narrower end of said wall further comprises a longitudinal extension of said wall beyond said ring, and a plurality of longitudinal channels each extending continuously through said part of said wall carrying said ring and through said extension of said wall and having a width smaller than the width between two adjacent spacing strips, said channels receiving terminal pins forming extensions of said segments when said segments are fully inserted into said cage.
 8. A device as claimed in claim 7, further comprising individual stoP members integral with said ring on the inner side of said wall and projecting for a short distance from said ring in the direction toward the wider end of said wall, one end of each of said segments at the point to which one of said terminal pins is connected abutting against at least one of said stop members when said segments are inserted into said cage.
 9. A device as defined in claim 2, in which after said segments are inserted into said cage, said cage is shrunk whereby said slots are closed and said segments are tightly clamped between the adjacent spacing strips and said peripheral wall of said cage is changed from its original conical shape to a cylindrical shape. 